601 research outputs found
Wave-particle interactions in the outer radiation belts
Data from the Van Allen Probes have provided the first extensive evidence of
non-linear (as opposed to quasi-linear) wave-particle interactions in space
with the associated rapid (fraction of a bounce period) electron acceleration
to hundreds of keV by Landau resonance in the parallel electric fields of time
domain structures (TDS) and very oblique chorus waves. The experimental
evidence, simulations, and theories of these processes are discussed. {\bf Key
words:} the radiation belts, wave-particle interaction, plasma waves and
instabilitiesComment: 9 pages, 2 figure
Double lepton pair production with electron capture in relativistic heavy--ion collisions
We present a theoretical study of a double lepton pair production in
ultra--relativistic collision between two bare ions. Special emphasis is placed
to processes in which creation of (at least one) pair is accompanied
by the capture of an electron into a bound ionic state. To evaluate the
probability and cross section of these processes we employ two approaches based
on (i) the first--order perturbation theory and multipole expansion of Dirac
wavefunctions, and (ii) the equivalent photon approximation. With the help of
such approaches, detailed calculations are made for the creation of two
bound--free pairs as well as of bound--free and free--free
pairs in collisions of bare lead ions Pb. The results of
the calculations indicate that observation of the double lepton processes may
become feasible at the LHC facility.Comment: 12 pages, 1 figur
Ground state hyperfine splitting of high Z hydrogenlike ions
The ground state hyperfine splitting values of high Z hydrogenlike ions are
calculated. The relativistic, nuclear and QED corrections are taken into
account. The nuclear magnetization distribution correction (the Bohr-Weisskopf
effect) is evaluated within the single particle model with the g_{S}-factor
chosen to yield the observed nuclear moment. An additional contribution caused
by the nuclear spin-orbit interaction is included in the calculation of the
Bohr-Weisskopf effect. It is found that the theoretical value of the wavelength
of the transition between the hyperfine splitting components in ^{165}Ho^{66+}
is in good agreement with experiment.Comment: 12 pages, Late
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